Trinomial nomenclature is used in case of
(a) Sympatric species
(b) Allochronic species
(c) Polytypic species
(d) Sibling species

Options

A. Sympatric species
B. Allochronic species
C. Polytypic species
D. Sibling species

Answer

To solve the question regarding trinomial nomenclature, we need to understand what trinomial nomenclature is and which type of species it is applied to. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand Trinomial Nomenclature
Trinomial nomenclature is a system of naming organisms that includes three parts: the genus name, the species name, and a third term that usually denotes a subspecies or variety. This system is an extension of the binomial nomenclature, which only includes the genus and species.

### Step 2: Identify the Types of Species
The question provides four options regarding the types of species:
- (a) Sympatric species: Species that live in the same geographic area and often interact.
- (b) Allochronic species: Species that are separated by time, meaning they do not coexist.
- (c) Polytypic species: Species that have multiple subspecies or varieties, often due to geographical or ecological differences.
- (d) Sibling species: Species that are very similar in appearance and behavior but are genetically distinct.

### Step 3: Relate Trinomial Nomenclature to the Types of Species
Trinomial nomenclature is specifically used for polytypic species. These species can have different subspecies that exhibit minor variations in traits due to their adaptation to different environments or geographical locations.

### Step 4: Conclusion
Based on the understanding that trinomial nomenclature is used to identify subspecies within a polytypic species, the correct answer to the question is:
**(c) Polytypic species.**